The annual Paris-Dakar road rally may find hard going when it crosses from Morocco to Western Sahara, where the Polisario Front independence movement has threatened to take up arms against the intruders. The 6,200 mile race across southern Europe and North Africa is scheduled to begin in Paris Jan. 1. It should arrive at the Western Sahara border Jan. 4, and then all bets are off. Last year threats from Algerian terrorists prompted a rerouting of the race and an airlift of competitors. If you’re competing this year or just along for the ride, expect disruptions, or worse.